许昌近20年初雪天气特征分析

Analysis of the Weather Characteristics of Early Snow in Xuchang in the Past 20 Years

气象上将雨、雪、雹等从天空下降至地面的水汽凝结物,称为“降水”。雪是由大量白色不透明的冰晶(雪晶)和其聚合物(雪团)组成的降水,是水汽遇冷的产物。基于降雪形成的条件,整理近2001—2020年许昌市5个站点的地面资料、探空资料、NCEP再分析资料,分析许昌市初雪出现的时空分布特征,根据影响系统对造成许昌市初雪的环流形势进行分类,结合典型个例给出各种环流形势特点;通过大量个例找出对许昌初雪有影响的天气尺度系统,分析产生初雪的物理量特征,得出初雪天气的具体预报特征。

Meteorology refers to the condensation of water vapor such as rain,snow,and hail that falls from the sky to the ground,known as“precipitation”.Snow is a precipitation composed of a large number of white opaque ice crystals(snow crystals)and their polymers(snow masses),which are the products of water vapor cooling.Based on the conditions of snowfall formation,the ground data,sounding data,and NCEP reanalysis data of 5 stations in Xuchang City from 2001 to 2020 were compiled to analyze the spatiotemporal distribution characteristics of early snow occurrence in Xuchang City.The circulation situation causing early snow in Xuchang City was classified according to the impact system,and various circulation situation characteristics were given based on typical cases.Through a large number of individual cases.identify the weather scale systems that have an impact on the early snow in Xuchang,analyze the physical characteristics that produce the early snow,and obtain the specific forecast characteristics of the early snow weather.